PHP shell_exec 等待脚本完成?

I have a PHP script that queries a database for a list of jobs to be done and fires off other PHP scripts based on what it finds in the database (basically a process queue).

Some of the scripts that the queue runner script executes may take 30 seconds or so to finish running (generating PDFs, resizing images, etc).

The problem is that shell_exec() in the queue runner script calls the processing scripts, but then doesn't wait for them to finish, resulting in the queue not being completed.

Queue runner script:

#!/usr/bin/php
<?php
    // Loop through database and find jobs to be done
    shell_exec(sprintf("/root/scripts/%s.php", $row['jobName']));
?>

Job script:

#!/usr/bin/php
<?php
    shell_exec("/usr/bin/htmldoc -t pdf --webpage test.html > test.pdf");
    // Update database to mark job as completed
?>

Running the job script directly from the command line works and the PDF is created.

Any ideas on how to fix this? Or a better way to run a process queue?

解决方案

Try this:

shell_exec("nohup /usr/bin/htmldoc -t pdf --webpage test.html > test.pdf 2>&1 &");